A flesh-eating parasite has been found just 25 miles from the United States border, marking its closest approach to U.S. soil since at least September 2025. The U.S. Department of Agriculture confirmed that the New World screwworm was detected this past Thursday in a 5-year-old goat in the Mexican state of Coahuila, which borders southwestern Texas.
Federal data shows that U.S. officials are currently tracking 32 cases of the parasitic fly within Coahuila, including 19 that remain active. Across Mexico, the scale of the outbreak is much larger, with at least 26,216 cases identified and more than 2,700 still active.
The New World screwworm is a parasitic fly that targets warm-blooded animals and humans. According to the Centers for Disease Control and Prevention, the fly lays its eggs in open wounds or natural body orifices such as the eyes, ears, nose, and mouth.
Once these eggs hatch, the larvae feed on the host’s living tissue and flesh. While historically confined to South America and parts of the Caribbean, the CDC notes that the parasite has been steadily migrating north through Central America and Mexico over the last three years.
Despite the shrinking distance, the USDA maintains a dedicated webpage stating that the pest “is not currently present” inside the United States. The department, which updates its data twice a week for any cases found within 400 miles of the border, stated that “the current risk to livestock, other animals, and people in the United States remains very low.”
Even so, the parasite has been steadily closing the gap over the last few years. Texas outdoor enthusiasts have been under an official advisory since late 2024, when the Texas Parks and Wildlife Department first warned of a case found in a cow in southern Mexico. This past April, Texas Agriculture Commissioner Sid Miller announced the parasite had moved within 60 miles of the border. This latest goat infection cuts that distance more than in half.
The threat is not entirely foreign to U.S. health officials. Last year, the Department of Health and Human Services confirmed the first-ever U.S. case of a New World screwworm infestation in a human.
That case involved a traveler who had recently returned to Maryland from El Salvador. Department of Health and Human Services spokesperson Andrew Nixon stated at the time that the infection was isolated to the traveler. Maryland health officials later confirmed that the individual fully recovered, and investigators found zero evidence that the parasite had spread to any other local people or animals.
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